EQT Midstream Partners, LP (Details) $ / shares in Units, $ in Thousands							6 Months Ended
	Jul. 21, 2015 USD ($) $ / shares	May. 15, 2015	Mar. 30, 2015 USD ($) mi	Mar. 17, 2015 USD ($) shares	Mar. 11, 2015 USD ($)	Feb. 17, 2015	Jun. 30, 2015 USD ($) shares	Jun. 30, 2014 USD ($)	Apr. 15, 2015 USD ($)	Dec. 31, 2012 shares
Subsidiary or equity method investee
Proceeds from offerings, net of underwriters' discounts and structuring fees							$ 696,582	$ 902,451
Ownership interest							30.20%
Changes in ownership of consolidate subsidiary							$ (72,954)
Increase to deferred tax liability							73,000
MVP Interest In Joint Venture
Subsidiary or equity method investee
Consideration			$ 54,200
Ownership interest			100.00%
EQT Energy Supply, LLC
Subsidiary or equity method investee
Total consideration									$ 124,300
EQM
Subsidiary or equity method investee
Number of subordinated units | shares										17,339,718
Conversion ratio						1
Number of common units issued to the public in an offering | shares				8,250,000
Proceeds from offerings, net of underwriters' discounts and structuring fees				$ 696,600
Offering expenses				24,500
EQM | NWV Gathering
Subsidiary or equity method investee
Consideration				925,700
Cash consideration				$ 873,200
EQM | MVP Holdco
Subsidiary or equity method investee
Ownership interest			100.00%
EQM | Mountain Valley Pipeline
Subsidiary or equity method investee
Ownership interest			55.00%
EQM | MVP Interest In Joint Venture
Subsidiary or equity method investee
Capital contribution reimbursement					$ 8,300
EQM | WGL Holdings, Inc.
Subsidiary or equity method investee
Ownership interest					7.00%
EQM | Vega Energy Partners, Ltd.
Subsidiary or equity method investee
Ownership interest					3.00%
EQM | Common Partner Units | Partnership Interest | NWV Gathering
Subsidiary or equity method investee
Number of common units representing limited partner interest | shares				511,973
EQM | General Partner Units | Partnership Interest | NWV Gathering
Subsidiary or equity method investee
Number of common units representing limited partner interest | shares				178,816
Mountain Valley Pipeline
Subsidiary or equity method investee
Length of natural gas interstate pipeline (in miles) | mi			300
Common Stock
Subsidiary or equity method investee
Changes in ownership of consolidate subsidiary				$ 122,800			122,833
Noncontrolling Interests in Consolidated Subsidiaries
Subsidiary or equity method investee
Changes in ownership of consolidate subsidiary				$ 195,800			$ (195,787)
Limited Partner Common
Subsidiary or equity method investee
Number of common units issued to the public in an offering | shares				1,237,500
Number of common units | shares							21,811,643
Ownership interest		90.10%
General Partner
Subsidiary or equity method investee
Number of general partner units | shares							1,443,015
General partner's interest							2.00%
General Partner | EQM | Subsequent Event
Subsidiary or equity method investee
Cash distribution declared (in dollars per share) | $ / shares	$ 0.64
Cash distribution declared	$ 1,100
Cash distribution declared related to IDRs	$ 10,100